Asymmetric bicycle chain link

ABSTRACT

A bicycle chain includes inner link members and outer link member. An inner link having two connecting openings which are formed at a distance from each other, pass through the inner link in the thickness direction thereof and are each designed for receiving a connecting component in order to connect the inner link to a further inner link in order to form an inner link member of a bicycle chain. An outer link member may be formed and attached to the inner link. The inner and/or outer links may be formed with features asymmetric about various orientations of the links.

This application claims priority to, and/or the benefit of, Germanpatent application DE 10 2018 207 361.9, filed May 11, 2018, thecontents of which are incorporated herein in their entirety.

FIELD OF INVENTION

The invention relates to a bicycle chain or chain drive system, andspecifically to a bicycle chain having links configured in an asymmetricmanner.

BACKGROUND

A bicycle chain inner link is known from EP 2 535 616 A or else fromU.S. Pat. No. 4,265,134 A. The bicycle chain inner links known fromthese documents (also only called “inner links” below) are in each caseformed mirror-symmetrically both with respect to a plane of symmetryorthogonally intersecting the connecting straight line in thelongitudinal center thereof and with respect to a plane of symmetrycontaining the connecting straight line and running in the thicknessdirection, which facilitates the mountability of said bicycle chaininner links. This is because it is then sufficient merely to payattention to the differently configured inner and outer sides of theinner link while, when inner and outer sides of the inner link arecorrectly oriented, an orientation error of the inner link duringmounting of the chain is impossible.

The abovementioned flat surfaces which surround the connecting openingson the inner side of the inner link are designed as contact surfaces forthe contact of end sides of chain rollers. One chain roller isaccommodated rotatably in each case on each connecting component whichconnects two opposite inner links to form an inner link member. Such aconnecting component can be, for example, a connecting pin or aconnecting rivet or a multi-part connecting component.

When a bicycle chain is arranged in an operationally ready state on thebicycle, the axial direction defined by the axis of the rear wheel hubis parallel to the thickness direction of the chain links. These twodirectional details are therefore equivalent. To avoidmisunderstandings, for the description of the constructive relationshipsof the bicycle chain and rear wheel pinion arrangement, use is made ofthe orthogonal system of coordinates of the inner link, that isintroduced at the beginning, consisting of longitudinal direction,thickness direction and width direction.

With the decades-old trend in bicycle engineering for increasing thenumber of pinions on the rear wheel hub, in order to obtain as fine agradation as possible of the transmission of torque from the pedalcranks to the rear wheel hub, the pinion distances between adjacentpinions have become smaller, the pinions have become thinner and thechains narrower. The abovementioned depression region is, for example, aresult of the bicycle chains becoming ever narrower in the thicknessdirection of the inner links. This is because, at least in that regionof an inner link intermediate space, into which a pinion tooth enters inorder to produce a meshing engagement with an inner link member of thebicycle chain, the link distance, which is to be measured in thethickness direction, between the inner sides of the inner links islocally increased by means of the depression region in comparison to thelink distance in the region between the flat surfaces of mutuallyopposite inner links. This facilitates the entry of the pinion into theinner link intermediate space. The inner link intermediate space isbounded here in the longitudinal direction of the inner link member bythe two chain rollers, which follow each other in the longitudinaldirection, of the inner link member and is bounded in the thicknessdirection by the two inner links of the inner link member, between whichinner links the chain rollers are arranged.

U.S. Pat. No. 4,265,134 A thus expressly discloses forming thedepression region from each side edge of the inner link towards theconnecting straight line with a decreasing longitudinal dimension, i.e.with a dimension parallel to the connecting straight line, in orderthereby to obtain a recess on the inner sides of the inner links, therecess tapering into the inner link intermediate space. This is intendedto particularly facilitate entry of a pinion tooth into the inner linkintermediate space.

With an increasing number of pinions and therefore with a decreasinglink distance between the links of the individual bicycle chain members,ever more precise guiding of the chain in the driving mode is requiredsince the engagement locations between the bicycle chain and theindividual pinions of a rear wheel pinion cassette, which pinions areassigned individual transmission ratios, lie increasingly closer to oneanother along the rear wheel axle.

SUMMARY

In an embodiment, a bicycle chain inner link is provided. The bicyclechain inner link includes two connecting openings which are formed at adistance from each other, pass through the inner link in the thicknessdirection thereof and are each designed for receiving a connectingcomponent in order to connect the inner link to a further inner link inorder to form an inner link member of a bicycle chain. A connectingstraight line connecting respective center axes of the connectingopenings defines a longitudinal direction of the inner link, and whereina direction orthogonal both with respect to the longitudinal directionand also with respect to the thickness direction is a width direction ofthe inner link. The inner link has, on its inner side facing the furtherinner link of the same inner link member in the completely mounted statein a bicycle chain, two flat surfaces which are provided at a distancefrom each other in the longitudinal direction of the inner link; and areseparated by a depression region, which is placed in the longitudinaldirection between them, and of which each flat surface surrounds anotherof the connecting openings. The depression region is set back withrespect to the flat surfaces towards an outer side of the inner linkthat is opposite the inner side. A distance, to be measured along thelongitudinal direction, between the flat surfaces changes along thewidth direction in such a manner that a location situated between twodistance regions having in each case greater distance values and havingthe smallest, but finitely large minimum distance value is situated at adistance away from the connecting straight line in the width direction.

In an embodiment, a bicycle chain outer link is provided. The bicyclechain outer link includes two connecting openings which are formed at adistance from each other, pass through the outer link in the thicknessdirection thereof and are each designed for receiving a connectingcomponent in order to connect the outer link to a further outer link inorder to form an outer link member of a bicycle chain. A connectingstraight line connecting respective center axes of the connectingopenings defines a longitudinal direction of the outer link. A directionorthogonal both with respect to the longitudinal direction and withrespect to the thickness direction is a width direction of the outerlink. The outer link has, on its inner side facing the further outerlink of the same outer link member in the completely mounted state in abicycle chain, two flat surfaces which are provided at a distance fromone another in the longitudinal direction if the outer link and areseparated by a depression region, which is placed in the longitudinaldirection between them, and of which each flat surface surrounds anotherof the connecting openings. The depression region is set back withrespect to the flat surfaces towards an outer side of the outer linkthat is opposite the inner side. In a minimum distance region containingthe connecting straight line and extending in the width direction, thedistance, to be measured in the longitudinal direction, between the flatsurfaces is minimal. The distance between the flat surfaces startingfrom the minimum distance region becomes larger towards each of the twoside edges bounding the outer link in the width direction.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be explained in more detail below withreference to the attached drawings, in which:

FIG. 1 illustrates a schematic side view of a bicycle with a chain ringof the present application, which chain ring uses inner links or/andouter links of the present application, in a view in a directionparallel to the rear wheel axle,

FIG. 2 illustrates a schematic side view of a drive assembly consistingof chain ring, front sprocket, rear pinion arrangement and rearderailleur from FIG. 1, in a view in a direction parallel to the rearwheel axle,

FIG. 3 illustrates a perspective view of a meshing engagement of thechain ring of FIGS. 1 and 2 with the front sprocket,

FIG. 4A illustrates a schematic elevation view of a first embodiment ofan inner side of an inner link of the chain ring of FIGS. 1 to 3, in aview in a direction parallel to the thickness direction T,

FIG. 4B illustrates a schematic bottom view of the inner link from FIG.4A, in a view along the arrow IV-B in FIG. 4A,

FIG. 4C illustrates a schematic top view of the inner link from FIG. 4A,in a view along the arrow IV-C in FIG. 4A,

FIG. 4D illustrates a schematic perspective view of the outer side ofthe inner link from FIG. 4A,

FIG. 5 illustrates a schematic elevation view of a second embodiment ofan inner side of an inner link of the chain ring of FIGS. 1 to 3, in aview in a direction parallel to the thickness direction T,

FIG. 6 illustrates a schematic elevation view of a third embodiment ofan inner side of an inner link of the chain ring of FIGS. 1 to 3, in aview in a direction parallel to the thickness direction T,

FIG. 7 illustrates a schematic elevation view of a first embodiment ofan inner side of an outer link of the chain ring of FIGS. 1 to 3, in aview in a direction parallel to the thickness direction T, and

FIG. 8 illustrates a schematic elevation view of a second embodiment ofan inner side of an outer link of the chain ring of FIGS. 1 to 3, in aview in a direction parallel to the thickness direction T.

DETAILED DESCRIPTION OF THE DRAWINGS

It is therefore the object of the present invention to provide atechnical teaching which permits as precise a guidance of a bicyclechain as possible even if the bicycle chain having outer and inner linkmembers in an alternating manner has a very narrow design for engagementwith a rear wheel pinion arrangement, for example having 10 or morepinions.

This object is achieved according to the invention by a bicycle chaininner link of the type mentioned at the beginning which is designed asan asymmetric bicycle chain inner link, and therefore a distance, to bemeasured along the longitudinal direction, between the flat surfaceschanges along the width direction in such a manner that a locationsituated between two distance regions having in each case greaterdistance values and having the smallest, but finitely large minimumdistance value is situated at a distance away from the connectingstraight line in the width direction.

In the prior art, for the driving mode as intended, the bicycle chainhas frequently been structurally configured solely in respect of itsmeshing engagement with the pinions of the rear wheel pinionarrangement. The fact that the bicycle chain, which can be shifted by arear derailleur between the individual pinions of the rear wheel pinionarrangement, is not only in engagement with the pinions of the rearwheel pinion arrangement, but also with the rollers of the derailleur,has frequently been disregarded. Particularly the chain guiding rollerwhich positions the bicycle chain along the rear wheel axle has animportant role here.

During the revolving on the bicycle, an inner link of a bicycle chain,which is designed to form a chain ring and revolves in a self-containedmanner, starting from a front sprocket generally reaches, in thesequence mentioned, first of all the tensioning roller and then thechain guiding roller of the derailleur, subsequently the meshing pinion,which is selected by positioning of the derailleur, and finally thesprocket again. In the process, the chain guiding roller and the meshingpinion engage on the chain ring on different sides thereof.Consequently, in the driving mode, the teeth of the chain guidingroller, which teeth are customarily formed with a considerably lowertooth height than the teeth of the pinions, and the teeth of the meshingpinion enter into the inner link intermediate space from opposite sides.

The chain does indeed always run over the same chain guiding roller anddoes not have to be shifted from the latter to another, as is the caseduring a shifting operation on the rear wheel pinion arrangement.Nevertheless, bicycle chain dimensions becoming increasingly moreextreme can also lead to problems with the engagement between the chainguiding roller and the bicycle chain, which can comprehensibly adverselyaffect the shifting precision on the rear wheel hub.

With the inner link presented above, it is extremely advantageouslypossible to optimally design the inner side of the inner link, whichinner side faces the respective tooth during a meshing engagement, bothfor the meshing engagement with the pinion generally having higherpinion teeth and for the meshing engagement with the chain guidingroller generally having lower roller teeth. Both the pinion tooth andthe roller tooth taper from their tooth root towards their tooth tip.The tooth height of the pinion tooth here is generally of such amagnitude that the pinion tooth projecting into the inner linkintermediate space projects, starting from the one side edge, which isthe entry side therefor, of the inner link in the width direction of theinner link or of the inner link member beyond the connecting straightline. In contrast thereto, the tooth height of a roller tooth of thechain guiding roller is generally of such a low magnitude that theroller tooth projecting into the inner link intermediate space, startingfrom the other, opposite side edge, which is the entry side for theroller tooth, does not reach in the width direction as far as theconnecting straight line. Since, on the presented inner link, theminimum distance value of the longitudinal distance between the flatsurfaces is placed at a distance away from the connecting straight linein the width direction, and since furthermore there is a greaterdistance between the flat surfaces in the width direction on both sidesof the location of the minimum distance value, the presented inner linktakes into account both the structural differences of pinion tooth androller tooth and the engagement situations arising with said teeth. Thesame applies to an inner link member which is formed by two identicalinner links lying mirror-symmetrically opposite each other.

Chain links are customarily constricted in the width direction in theregion of the longitudinal center of the connecting straight line, i.e.a chain link has a smaller width dimension in the region of thelongitudinal center of the connecting straight line than in the regionof the connecting openings. In an advantageous manner, in addition tothe engagement of a tooth in the inner link intermediate space, a sideedge of the inner link can stabilise the inner link at the respectivetooth-carrying component by the fact that the distances of those sideedge portions of the inner link that run in the longitudinal directionbetween the connecting openings away from the connecting straight linein the width direction differ in size on different sides of theconnecting straight line.

Since, firstly, the pinion teeth project in the width direction moredeeply into the inner link intermediate space than the roller teeth, andsince, furthermore, the bicycle chain is always in engagement with thesame chain guiding roller, but with pinions of different diameter, theside edge of the inner link having the greater distance away from thelongitudinal center of the connecting straight line is preferably theside edge on the inlet side for a roller tooth. This means that thelocation of the minimum distance value with respect to the connectingstraight line is preferably situated on that side of the inner link onwhich the distance of the side edge portion away from the connectingstraight line is greater. Therefore, even for a roller tooth with ashort tooth height, wall portions overlapping with the roller tooth inthe width direction can be provided on the inner side of the inner link,said wall portions reliably guiding the inner link and the bicycle chainformed by it on the guide roller in the thickness direction. Since, incontrast to the pinions with which the chain enters into engagement, theradius of curvature of the chain guiding roller does not change, theside edge on the inlet side for the roller tooth can be configured insuch a manner that, during engagement of a roller tooth, said side edgelies against an outer surface of the one roller body of the chainguiding roller and thus additionally stabilises the bicycle chain, whichis formed with the participation of the presented inner link, on thechain guiding roller.

As stable a lateral guidance as possible in the thickness direction ofan inner link member, which is formed by the presented inner link, on aroller tooth with a short tooth height can be achieved in that the sideedge portion with the greater distance away from the connecting straightline runs rectilinearly parallel to the latter. The rectilinear sideedge portion can then lie in a stabilising manner as a tangent againsta, for example, doubly conical, roller body of the chain guiding roller.

In contrast to the chain guiding roller, a pinion body situated radiallywithin the teeth of a pinion does not contribute to the guiding of thechain on the pinion. In order to save weight, on the one hand, and foreasier production of a meshing engagement with a pinion during ashifting operation, on the other hand, preferably the opposite side edgeportion having the smaller distance away from the longitudinal center ofthe connecting straight line is therefore designed in such a manner thatit first of all along its profile in the longitudinal directionapproaches the connecting straight line and then moves away from thelatter again. This constriction makes it possible to reduce the amountby which the connecting straight line of the inner link has to be raisedover a pinion tooth tip in order, particularly during the shiftingoperation onto a pinion of larger diameter, to shift the pinion toothtip, which is initially situated outside an inner link member in thethickness direction, into the region between the two inner links.

An advantageous engagement situation both with pinion teeth and withroller teeth of the chain guiding roller can be achieved by the factthat the location of the minimum distance value is situated closer inthe width direction to a side edge portion of the inner link, which sideedge portion runs between the connecting openings in the longitudinaldirection, than the connecting straight line. In case of doubt, thedistance between the location of the minimum distance value and a sideedge portion should be determined in the longitudinal direction whereverthe side edge portion has approached the connecting straight line to thegreatest extent in the width direction.

In order to be able to use the depression region of an inner link as aninsertion aid of a tooth into the inner link intermediate space or/andas an approximately negative form-fitting contour of a tooth alreadyintroduced into the inner link intermediate space, in an advantageousdevelopment of the present invention, in the width direction on bothsides of the connecting straight line, in each case at a distance fromthe location of the minimum distance value, there can be in each case alocation of a maximum distance value at which the distance, which occurson the respective side of the connecting straight line on the inner sideof the inner link and is to be measured in the longitudinal direction,between the two flat surfaces is greatest. For clarity, it should beemphasised that each of the two maximum distance values is greater interms of amount than the minimum distance value. On account of theasymmetry, which exists in the width direction of the inner links, ofthe presented inner link, the distance of the location of the minimumdistance value away from the respective locations of the maximumdistance values preferably differs in size.

The depression region preferably completely passes through the innerlink in the width direction.

The location of the minimum distance value can be merely a virtuallypoint-shaped location in the width direction without a significantdimension in the width direction, or it can be a minimum distance valuerange extending over a predetermined distance in the width direction.

In principle, an edge of a flat surface in the region between theconnecting openings can have a curved profile, and also the radiallyouter edges of the chain rollers lying with their end sides against theflat surfaces can have a curved, namely circular profile. During theengagement of a pinion tooth or else of a roller tooth in an inner linkintermediate space, it can be overall advantageous for the stability ofthe inner link member formed by the presented inner links and thereforeof a bicycle chain having such inner link members if at least one flatsurface protrudes radially over the cylindrical outer surface of a chainroller with respect to a center axis, running in the thicknessdirection, through the connecting openings. This makes it possible toprevent that, during the production of a meshing engagement betweentooth and inner link member, a portion of the tooth tip penetratesbetween chain roller and inner link and thus possibly expands or evenbreaks the inner link member in the thickness direction. Saidadvantageous local radial protrusion of the flat surface over the chainroller can be provided by the fact that, in a longitudinal region of theinner link situated between the connecting openings, the edge of atleast one flat surface runs in the width direction rectilinearly atleast in portions or with a greatest radius of curvature along thesurface edge encircling the connecting opening. For the reasonsmentioned, the edges of the two flat surfaces preferably runrectilinearly at least in portions on both sides of the depressionregion in the longitudinal region of the inner link.

Whenever, in said longitudinal region, the edges of the two flatsurfaces run rectilinearly at least in portions, the rectilinear edgeportions of the edges of the flat surfaces can run parallel to oneanother at least in portions. The width portion in which the rectilinearedge portions of the edges of the flat surfaces run, then preferablyforms the abovementioned minimum distance value region. This is ofadvantage, for example, if the pinion arrangement interacting with theinner link has numerous pinion teeth of differing tooth height. Thedepression region can then continue to serve as an insertion aid forsaid different pinion teeth into the inner link intermediate space and,for a multiplicity of different pinion teeth, is formed after productionof the meshing engagement, for the defined arrangement of said pinionteeth in the inner link intermediate space.

Whenever, in said longitudinal region, the edges of the two flatsurfaces run rectilinearly at least in portions, a very precise guidanceof the inner link members and therefore of the chain by the inner linkby way of pinion teeth tapering towards the tooth tip can be provided bythe fact that the distance, which is to be recovered in the longitudinaldirection, of the rectilinear portions is reduced at least in portionsfrom edges of the flat surfaces in the width direction as they approachcloser to the location of the minimum distance value. Although thisreduction can also take place in a stepwise manner, a continuousstepless reduction of said distance is preferred in respect of thecontour of the pinion tooth, but also roller tooth, which enters intothe inner link intermediate space and is temporarily accommodated there.

For the engagement with the pinion teeth and also with the roller teethon both sides of the location of the minimum distance value,rectilinearly running portions of the edges of the flat surfaces can beformed, the distance of which portions is reduced in the longitudinaldirection as they approach the location of the minimum distance value.

In order, firstly, to be able to adapt the profile of a flat surface tothe configuration of the chain roller lying thereagainst and in order,secondly, to be able to provide an edge of the flat surface, which edgeis as kink-free or/and as jump-free as possible and therefore promotesentry of a tooth into the inner link intermediate space, in alongitudinal region of the inner link, which longitudinal region issituated between the connecting openings, the edge of at least one flatsurface can run in the width direction in a manner curved continuouslyin the same direction. The profile of the edge of the flat surface canthen be particularly readily adapted to the contour, which taperstowards the tooth tip, in particular of a pinion tooth if the curvedprofile of the edge of the flat surface is assigned changing radii ofcurvature along the width direction. The radii of curvature preferablybecome smaller with increasing distance from the location of the minimumdistance value, i.e. the curvature of the respective edge portionbecomes greater. Then, in addition, the abovementioned radial protrusionof the flat surface over the cylindrical circumferential surface of achain roller assigned to the flat surface for contact therewith can alsobe realized with a curved edge profile. This preferably holds true forboth flat surfaces of the inner link.

In principle, it should not be ruled out that the depression region isof convexly curved design in a width region containing the connectingstraight line, when looking at the inner link inner side, for example iscurved about an axis of curvature parallel to the connecting straightline. However, a greater inner link intermediate space available forreceiving a tooth can be obtained with a depression region which, in awidth region containing the connecting straight line, has a flat surfaceregion. In principle, said flat surface region can be inclined. Tofacilitate the introduction of a tooth into the inner link intermediatespace, the inclination, if it is present, is preferably such that thelink distance, to be measured in the thickness direction, of the flatsurface regions of two inner links lying mirror-symmetrically oppositeeach other of one and the same inner link member becomes greater towardsa side edge away from the minimum distance value in the width direction.However, a flat surface region which is orthogonal with respect to thethickness direction is preferred for providing as large a receivingvolume as possible of the inner link intermediate space.

The flat surface region, following the presented asymmetry of the innerlink, is preferably arranged offset towards a side edge region relativeto the connecting straight line in the width direction. The flat surfaceregion is preferably arranged offset towards that side edge region whichis situated closer to the location of the minimum distance value, andtherefore an insertion slope having a greater dimension in the widthdirection can be provided on the side edge portion on the inlet side forthe pinion tooth than on the side edge portion on the inlet side for theroller tooth, for example in the form of a chamfering. This facilitatesthe introduction of a pinion tooth into the inner link intermediatespace.

For simple but reliable definition of the distance between two innerlinks forming an inner link member and also furthermore as a definedaxle formation which can rotatably receive a chain roller, according toan advantageous development the connecting openings are radiallysurrounded within the flat surfaces surrounding them in each case bysleeve portions. The sleeve portions protrude in the thickness directionof the inner links over the flat surfaces surrounding said sleeveportions.

In order to obtain a bicycle chain which is as slender as possible inthe thickness direction of the links forming the latter, the outer sideof the inner link that is opposite the inner side preferably has a flatouter surface which both extends in the longitudinal direction betweenthe connecting openings, where, during a shifting operation, a sidesurface of a pinion tooth of a pinion coming into engagement by means ofthe shifting operation can enter into contact engagement, and also atleast partially surrounds the connecting openings where inner sideregions of an outer link can come into contact with the completelymounted bicycle chain. The flat outer surface preferably completelysurrounds the connecting openings.

It is indeed in principle not ruled out that the outer side of the innerlink also has, in addition to the flat outer surface, a further,non-flat outer surface. However, in order to obtain the abovementionedslender bicycle chain, it is preferred that the outer side is free fromprojections which protrude over the flat outer surface in the thicknessdirection.

By contrast, it should not only not be ruled out, but it is evenpreferred that the outer side of the inner link has hollows ordepression surrounding the connecting openings and in whichcorresponding projections on inner sides of outer links can engage inorder to position the inner link and an outer link adjoining the latterrelative to each other. In order also to obtain a centring effect, thedepressions are preferably formed tapering in a direction away from theflat outer surface. For example, the depressions can have a negativelyfrustoconical configuration.

For the proposed inner link, it then advantageously does not matter forthe running direction of the bicycle chain formed with the participationof said inner link if the inner side or/and the outer side, preferablythe entire inner link, is mirror-symmetrical with respect to a plane ofsymmetry orthogonal with respect to the connecting straight line.

The abovementioned object is also achieved by a bicycle chain outer linkhaving two connecting openings which are formed at a distance from eachother, pass through the outer link in the thickness direction thereofand are each designed for receiving a connecting component in order toconnect the outer link to a further outer link in order to form an outerlink member of a bicycle chain, wherein a connecting straight lineconnecting respective center axes of the connecting openings defines alongitudinal direction of the outer link, and wherein a directionorthogonal both with respect to the longitudinal direction and withrespect to the thickness direction is a width direction of the outerlink, wherein the outer link has, on its inner side facing the furtherouter link of the same outer link member in the completely mounted statein a bicycle chain, two flat surfaces which are provided at a distancefrom one another in the longitudinal direction of the outer link and areseparated by a depression region, which is placed in the longitudinaldirection between them, of which each flat surface surrounds another ofthe connecting openings, wherein the depression region is set back withrespect to the flat surfaces towards an outer side of the outer linkthat is opposite the inner side, wherein, in a minimum distance regioncontaining the connecting straight line and extending in the widthdirection, the distance, to be measured in the longitudinal direction,between the flat surfaces is minimal, wherein the distance between theflat surfaces starting from the minimum distance region becomes largertowards each of the two side edges bounding the outer link in the widthdirection.

Such an outer link can facilitate the introduction of a pinion toothinto the outer link intermediate space. The depression regions of outerlinks which are opposite one another in the thickness direction and areconnected by connecting components to form an outer link member of abicycle chain form a region on the outer link member, in which regionthe outer link member has a greater link distance, to be measured in thethickness direction, than, for example, in the region of the flatsurfaces which are designed for contact against outer sides of innerlinks. By means of the expansion of the depression regions in theapproach towards the side edges bounding the outer link in the widthdirection, the depression regions can act as introduction funnels forpinion teeth, and starting from virtually any arrangement of a piniontooth tip in the entry region of an outer link intermediate space, canguide pinion teeth into said intermediate space.

What has been stated at the beginning with regard to the connectingcomponents of inner link members holds true for the connectingcomponents of outer link members.

The distance between the flat surfaces does not have to become smallercontinuously from the side edge as far as the minimum distance region.It is entirely sufficient if a change in the distance between the flatsurfaces substantially takes place in a region situated close to therespective side edge. As a result, an advantageously stiff outer linkcan be obtained. Depending on how the edge of the respective flatsurfaces runs in the region in which the flat surfaces are adjacent tothe depression region in the longitudinal direction, an outer link whichboth promotes the entry of a pinion tooth into the outer linkintermediate space and is also advantageously stiff can be obtained inthat, for at least one width region of the outer link, it holds truethat a distance, to be measured in the longitudinal direction, betweenportions of edges, which are adjacent to the depression region, of theflat surfaces changes more greatly in the 50%, preferably 30%,particularly preferably 10% of the width dimension of the width regionthat is situated closest to the longitudinal center of the side edgethan in the 30%, preferably 40%, particularly preferably 50% of thewidth dimension of the width region that is situated closest to theconnecting straight line.

Said width region of the outer link extends from the connecting straightline parallel to the width direction as far as the longitudinal centerof a side edge. Consequently, the outer link has two width regions, oneon each side of the connecting straight line. What has been stated abovepreferably holds true for both width regions of an outer link.

For a bicycle chain, it is important that inner and outer link memberswhich are connected to one another in an articulated manner via aconnecting component can be safely bent about the axis of the connectingcomponent. The neat revolution of the chain around sprockets, pinionsand rollers of different diameters can thereby be ensured. This ensuresthat the bicycle chain remains in engagement with the respectivetooth-carrying components of the bicycle and is not inclined, forexample, to jump from a sprocket or a pinion. One reason for anundesirable stiffening of a bicycle chain within the context ofincreased bending resistance is a penetration of particles into theregion between surface portions of inner and outer link lying againstone another.

A configuration of the outer link which promotes both entry of a piniontooth into the outer link intermediate space and also counteracts entryof particles between said surface portions of inner and outer link canadvantageously be achieved by the fact that the distance between theflat surfaces on the inner side of the outer link increases more greatlyin the direction of the one side edge on a first side of a referenceplane orthogonally intersecting the connecting straight line in itslongitudinal center than on the opposite, second side of the referenceplane. As a result, the edge of a flat surface can run congruently withthe outer edge of an end portion of an inner link, said end portionlying against said flat surface, and the edge of the second flatsurface, which is situated away in the longitudinal direction, canprotrude with respect to a center axis, running in the thicknessdirection, of the connecting opening, which is surrounded by said flatsurface, radially over the outer edge of an end portion of another innerlink, said end portion lying against said other flat surface. Thisradial protrusion prevents particles which are entrained, for example,by way of a soiled pinion tooth tip from approaching the gap existingbetween outer link and inner link.

Said radial protrusion does not exist, or exists in a smaller extent, onthe first-mentioned flat surface on the inner side of the outer link andthat end portion of the inner link which lies thereagainst.Nevertheless, even in the case of congruent edges of the flat surface ofthe outer link inner side and end portion of the inner link outer side,which edges are preferably chamfering-free in order to avoid dirtentering the gap between the inner and outer link, a narrow gap sizebetween the flat surface and end portion of the inner link can still bemaintained. This counteracts the entry of particles or even of a portionof a tooth tip into the gap. In the event of a congruent design, in saidregion both the edge of the flat surface of the outer link inner sideand the outer edge of the adjacent end portion of the inner link outerside are preferably formed in a circular manner with the center axis ofthe connecting component as center axis of the circular configuration.The congruence of the edge portions is then maintained over apredetermined relative movement portion of inner and outer linkirrespective of a relative rotation of outer link and inner link.

The distance preferably also increases to a differing extent in theopposite direction towards the respective other side edge on thedifferent sides of the reference plane, specifically particularlypreferably to a greater extent on the second side of the reference planethan on the first side thereof.

Tapering of the depression region from a side edge portion in the widthdirection towards the connecting straight line can be obtained under theabovementioned boundary conditions of an outer link which is notmirror-symmetrical and has advantageously jump- and kink-free edges of aflat surface in a region adjacent to the depression region in that, forthe flat surface, it holds true that a region of the edge of the flatsurface that is adjacent to the depression region is curved to adiffering degree in the width direction on different sides of theconnecting straight line. This preferably holds true for the two flatsurfaces of the inner side of the outer link, which flat surfaces eachsurround a different connecting opening.

A radial protrusion of a flat surface on one side of the connectingstraight line and a smaller radial protrusion or a profile of the edgeof the flat surface, which profile is congruent with the outer edge ofthe adjacent inner link, on the other side of the connecting straightline can be obtained in that, for the flat surface, it holds true thatthat region of the edge of the flat surface that is adjacent to thedepression region has a curved profile in portions in the widthdirection on one side of the connecting straight line and a rectilinearprofile in portions on the other side. This preferably holds true forthe two flat surfaces. This will be explained using the example of achain joint which is formed by an outer link member and an inner linkmember which is connected to the latter and trails in the drivingdirection of rotation of the chain ring formed by the bicycle chain. Onaccount of the trailing in the driving direction of rotation, the chainroller of the chain joint and optionally outer edge regions of the innerlinks holding the chain roller between them in the width direction arepermanently in torque-transmitting contact engagement with a piniontooth during a meshing engagement with a pinion. It can be advantageousthere to form the flat surfaces of the outer link inner sides, whichflat surfaces surround the connecting openings involved in the formationof said chain joint, on that side of the chain joint which faces thepinion axis, i.e. which are situated radially on the inside on the chainring, with a high radial protrusion with respect to the outer edges ofthose end regions of inner link outer sides which lie thereon. Bycontrast, on that side of the chain joint which is situated radially onthe outside of the chain ring, and also on that side of the chain joint,which leads in the driving direction of rotation, of the same outer linkmember that is situated radially on the inside, the mechanically lessgreatly loaded edges, which are therefore also less greatly exposed to arisk of soiling, of the flat surfaces can be formed with a smallerradial protrusion or congruently with the outer edge of the adjacentinner link end regions. Consequently, on the leading chain roller withrespect to the observed outer link intermediate space, an enlarged entryregion into the intermediate space is provided for a pinion tooth on theradially inner side of the chain ring.

The outer link can therefore be designed in accordance with the aboveexplanations in such a manner that a curved edge region portion of therespective other flat surface lies opposite that edge region portionwhich is rectilinear in portions in the longitudinal direction.Conversely, the same preferably holds true for the curved region of theedge of the same flat surface, i.e. that a rectilinear portion of anedge of the other flat surface lies opposite said curved region in thelongitudinal direction.

In principle, for easier introduction of a pinion tooth into the outerlink intermediate space, it is advantageous if, in a first width regionof the outer link, which width region extends from the connectingstraight line parallel to the width direction as far as the longitudinalcenter of the one side edge, the distance between edge portions of theflat surfaces that are adjacent to the depression region is at a maximumin the region of the longitudinal center of the one side edge. Foreasier production of an engagement even of a roller tooth with the outerlink intermediate space, with the roller tooth, by comparison with apinion tooth, entering the outer link intermediate space from theopposite direction in the width direction, it can therefore beadvantageous if in a second width region of the outer link, which widthregion extends from the connecting straight line parallel to the widthdirection in the opposite direction as far as the longitudinal center ofthe other side edge, the distance between edge portions of the flatsurfaces that are adjacent to the depression region is at maximum in theregion of the longitudinal of the other side edge. To facilitate themounting of such an outer link during the production of a bicycle chain,the maximum distances in the first and in the second width region arepreferably identical in size in terms of amount.

To facilitate an accurately fitting arrangement of outer link and innerlink during the production of a bicycle chain, each of the connectingopenings of the outer link on the inner side is preferably surroundedradially within the flat surface surrounding them by a projectionprotruding in the thickness direction over the respective flat surface.On the finished bicycle chain, said projection preferably projects intothe abovementioned depression on the outer side of an inner link andthus defines the relative position of outer link and inner link withrespect to their connecting openings, which are each aligned in order toform a chain joint. The projection is preferably designed tapering in adirection away from the respective flat surface, and therefore, inparticular in interaction with a depression tapering in the thicknessdirection into the inner link, said projection can deploy a centringeffect. The projection is preferably frustoconical.

Whenever the outer link has a depression region which is notmirror-symmetrical, to facilitate the mounting of said outer link, it isnevertheless preferably provided that the inner side or/and the outerside, preferably the entire outer link, is point-symmetrical withrespect to an axis of symmetry intersecting the connecting straight linein the longitudinal center thereof and running in the thicknessdirection. Symmetry present on the outer link eliminates the possibilityof an erroneous arrangement of the outer link on the bicycle chain.

For the facilitated mounting of the outer link with a considerablyreduced risk of error, it is therefore particularly preferred that theinner side or/and the outer side, preferably the entire outer link, ismirror-symmetrical both with respect to a first plane of symmetryorthogonally intersecting the connecting straight line in thelongitudinal center thereof and with respect to a second plane ofsymmetry running in the thickness direction and containing theconnecting straight line.

In addition, the present invention relates to a chain ring, comprising abicycle chain revolving in a self-contained manner and having outer andinner link members following one another in an alternating manner in therevolving direction, wherein the inner link members are formed from twoasymmetric inner links, as described above, or/and wherein the outerlink members are formed from two outer links designed as describedabove. Such a chain ring also embodies the technical advantagesassociated with the present invention and achieves the object mentionedat the beginning on account of the use of the links presented above.

As has already been described in detail above, the above-describedasymmetric inner link serves especially for forming preferred inner linkmembers which, with their one side edge, permit an extremelyadvantageous meshing engagement with a pinion of a rear wheel pinioncassette and which, with their side edge respectively opposite in thewidth direction, permit a particularly advantageous engagement with achain guiding roller of a derailleur. Inner link members consisting ofinner links, the two side edge portions of which are at a distance ofdiffering size from the connecting straight line in the width direction,are arranged on the chain ring, in order to obtain the advantageousengagement situations mentioned both with pinions and with the chainguiding roller, in such a manner that the side edge portions at thegreater distance from the connecting straight line are arranged lyingradially on the outside of the chain ring. This is because, during arevolution of the chain ring on a bicycle, the radially outer side ofthe chain ring is situated closer to a body of the chain guiding roller,while, during said revolution, the radially inner side of the chain ringis situated closer to a body of the meshing pinion of the rear wheelpinion arrangement.

This object is achieved according to the an embodiment by a bicyclechain inner link of the type mentioned at the beginning which isdesigned as an asymmetric bicycle chain inner link, and therefore adistance, to be measured along the longitudinal direction, between theflat surfaces changes along the width direction in such a manner that alocation situated between two distance regions having in each casegreater distance values and having the smallest, but finitely largeminimum distance value is situated at a distance away from theconnecting straight line in the width direction.

In the prior art, for the driving mode as intended, the bicycle chainhas frequently been structurally configured solely in respect of itsmeshing engagement with the pinions of the rear wheel pinionarrangement. The fact that the bicycle chain, which can be shifted by arear derailleur between the individual pinions of the rear wheel pinionarrangement, is not only in engagement with the pinions of the rearwheel pinion arrangement, but also with the rollers of the derailleur,has frequently been disregarded. Particularly the chain guiding rollerwhich positions the bicycle chain along the rear wheel axle has animportant role here.

During the revolving on the bicycle, an inner link of a bicycle chain,which is designed to form a chain ring and revolves in a self-containedmanner, starting from a front sprocket generally reaches, in thesequence mentioned, first of all the tensioning roller and then thechain guiding roller of the derailleur, subsequently the meshing pinion,which is selected by positioning of the derailleur, and finally thesprocket again. In the process, the chain guiding roller and the meshingpinion engage on the chain ring on different sides thereof.Consequently, in the driving mode, the teeth of the chain guidingroller, which teeth are customarily formed with a considerably lowertooth height than the teeth of the pinions, and the teeth of the meshingpinion enter into the inner link intermediate space from opposite sides.

The chain does indeed always run over the same chain guiding roller anddoes not have to be shifted from the latter to another, as is the caseduring a shifting operation on the rear wheel pinion arrangement.Nevertheless, bicycle chain dimensions becoming increasingly moreextreme can also lead to problems with the engagement between the chainguiding roller and the bicycle chain, which can comprehensibly adverselyaffect the shifting precision on the rear wheel hub.

With the inner link presented above, it is extremely advantageouslypossible to optimally design the inner side of the inner link, whichinner side faces the respective tooth during a meshing engagement, bothfor the meshing engagement with the pinion generally having higherpinion teeth and for the meshing engagement with the chain guidingroller generally having lower roller teeth. Both the pinion tooth andthe roller tooth taper from their tooth root towards their tooth tip.The tooth height of the pinion tooth here is generally of such amagnitude that the pinion tooth projecting into the inner linkintermediate space projects, starting from the one side edge, which isthe entry side therefor, of the inner link in the width direction of theinner link or of the inner link member beyond the connecting straightline. In contrast thereto, the tooth height of a roller tooth of thechain guiding roller is generally of such a low magnitude that theroller tooth projecting into the inner link intermediate space, startingfrom the other, opposite side edge, which is the entry side for theroller tooth, does not reach in the width direction as far as theconnecting straight line. Since, on the presented inner link, theminimum distance value of the longitudinal distance between the flatsurfaces is placed at a distance away from the connecting straight linein the width direction, and since furthermore there is a greaterdistance between the flat surfaces in the width direction on both sidesof the location of the minimum distance value, the presented inner linktakes into account both the structural differences of pinion tooth androller tooth and the engagement situations arising with said teeth. Thesame applies to an inner link member which is formed by two identicalinner links lying mirror symmetrically opposite each other.

Chain links are customarily constricted in the width direction in theregion of the longitudinal center of the connecting straight line, i.e.a chain link has a smaller width dimension in the region of thelongitudinal center of the connecting straight line than in the regionof the connecting openings. In an advantageous manner, in addition tothe engagement of a tooth in the inner link intermediate space, a sideedge of the inner link can stabilize the inner link at the respectivetooth carrying component by the fact that the distances of those sideedge portions of the inner link that run in the longitudinal directionbetween the connecting openings away from the connecting straight linein the width direction differ in size on different sides of theconnecting straight line.

Since, firstly, the pinion teeth project in the width direction moredeeply into the inner link intermediate space than the roller teeth, andsince, furthermore, the bicycle chain is always in engagement with thesame chain guiding roller, but with pinions of different diameter, theside edge of the inner link having the greater distance away from thelongitudinal center of the connecting straight line is preferably theside edge on the inlet side for a roller tooth. This means that thelocation of the minimum distance value with respect to the connectingstraight line is preferably situated on that side of the inner link onwhich the distance of the side edge portion away from the connectingstraight line is greater. Therefore, even for a roller tooth with ashort tooth height, wall portions overlapping with the roller tooth inthe width direction can be provided on the inner side of the inner link,said wall portions reliably guiding the inner link and the bicycle chainformed by it on the guide roller in the thickness direction. Since, incontrast to the pinions with which the chain enters into engagement, theradius of curvature of the chain guiding roller does not change, theside edge on the inlet side for the roller tooth can be configured insuch a manner that, during engagement of a roller tooth, said side edgelies against an outer surface of the one roller body of the chainguiding roller and thus additionally stabilizes the bicycle chain, whichis formed with the participation of the presented inner link, on thechain guiding roller.

As stable a lateral guidance as possible in the thickness direction ofan inner link member, which is formed by the presented inner link, on aroller tooth with a short tooth height can be achieved in that the sideedge portion with the greater distance away from the connecting straightline runs rectilinearly parallel to the latter. The rectilinear sideedge portion can then lie in a stabilizing manner as a tangent againsta, for example, doubly conical, roller body of the chain guiding roller.

In contrast to the chain guiding roller, a pinion body situated radiallywithin the teeth of a pinion does not contribute to the guiding of thechain on the pinion. In order to save weight, on the one hand, and foreasier production of a meshing engagement with a pinion during ashifting operation, on the other hand, preferably the opposite side edgeportion having the smaller distance away from the longitudinal center ofthe connecting straight line is therefore designed in such a manner thatit first of all along its profile in the longitudinal directionapproaches the connecting straight line and then moves away from thelatter again. This constriction makes it possible to reduce the amountby which the connecting straight line of the inner link has to be raisedover a pinion tooth tip in order, particularly during the shiftingoperation onto a pinion of larger diameter, to shift the pinion toothtip, which is initially situated outside an inner link member in thethickness direction, into the region between the two inner links.

An advantageous engagement situation both with pinion teeth and withroller teeth of the chain guiding roller can be achieved by the factthat the location of the minimum distance value is situated closer inthe width direction to a side edge portion of the inner link, which sideedge portion runs between the connecting openings in the longitudinaldirection, than the connecting straight line. In case of doubt, thedistance between the location of the minimum distance value and a sideedge portion should be determined in the longitudinal direction whereverthe side edge portion has approached the connecting straight line to thegreatest extent in the width direction.

In order to be able to use the depression region of an inner link as aninsertion aid of a tooth into the inner link intermediate space or/andas an approximately negative form fitting contour of a tooth alreadyintroduced into the inner link intermediate space, in the widthdirection on both sides of the connecting straight line, in each case ata distance from the location of the minimum distance value, there can bein each case a location of a maximum distance value at which thedistance, which occurs on the respective side of the connecting straightline on the inner side of the inner link and is to be measured in thelongitudinal direction, between the two flat surfaces is greatest. Forclarity, it should be emphasized that each of the two maximum distancevalues is greater in terms of amount than the minimum distance value. Onaccount of the asymmetry, which exists in the width direction of theinner links, of the presented inner link, the distance of the locationof the minimum distance value away from the respective locations of themaximum distance values preferably differs in size.

The depression region preferably completely passes through the innerlink in the width direction.

The location of the minimum distance value can be merely a virtuallypoint shaped location in the width direction without a significantdimension in the width direction, or it can be a minimum distance valuerange extending over a predetermined distance in the width direction.

In principle, an edge of a flat surface in the region between theconnecting openings can have a curved profile, and also the radiallyouter edges of the chain rollers lying with their end sides against theflat surfaces can have a curved, namely circular profile. During theengagement of a pinion tooth or else of a roller tooth in an inner linkintermediate space, it can be overall advantageous for the stability ofthe inner link member formed by the presented inner links and thereforeof a bicycle chain having such inner link members if at least one flatsurface protrudes radially over the cylindrical outer surface of a chainroller with respect to a center axis, running in the thicknessdirection, through the connecting openings. This makes it possible toprevent that, during the production of a meshing engagement betweentooth and inner link member, a portion of the tooth tip penetratesbetween chain roller and inner link and thus possibly expands or evenbreaks the inner link member in the thickness direction. Saidadvantageous local radial protrusion of the flat surface over the chainroller can be provided by the fact that, in a longitudinal region of theinner link situated between the connecting openings, the edge of atleast one flat surface runs in the width direction rectilinearly atleast in portions or with a greatest radius of curvature along thesurface edge encircling the connecting opening. For the reasonsmentioned, the edges of the two flat surfaces preferably runrectilinearly at least in portions on both sides of the depressionregion in the longitudinal region of the inner link.

Whenever, in said longitudinal region, the edges of the two flatsurfaces run rectilinearly at least in portions, the rectilinear edgeportions of the edges of the flat surfaces can run parallel to oneanother at least in portions. The width portion in which the rectilinearedge portions of the edges of the flat surfaces run, then preferablyforms the abovementioned minimum distance value region. This is ofadvantage, for example, if the pinion arrangement interacting with theinner link has numerous pinion teeth of differing tooth height. Thedepression region can then continue to serve as an insertion aid forsaid different pinion teeth into the inner link intermediate space and,for a multiplicity of different pinion teeth, is formed after productionof the meshing engagement, for the defined arrangement of said pinionteeth in the inner link intermediate space.

Whenever, in said longitudinal region, the edges of the two flatsurfaces run rectilinearly at least in portions, a very precise guidanceof the inner link members and therefore of the chain by the inner linkby way of pinion teeth tapering towards the tooth tip can be provided bythe fact that the distance, which is to be recovered in the longitudinaldirection, of the rectilinear portions is reduced at least in portionsfrom edges of the flat surfaces in the width direction as they approachcloser to the location of the minimum distance value. Although thisreduction can also take place in a stepwise manner, a continuousstepless reduction of said distance is preferred in respect of thecontour of the pinion tooth, but also roller tooth, which enters intothe inner link intermediate space and is temporarily accommodated there.

For the engagement with the pinion teeth and also with the roller teethon both sides of the location of the minimum distance value,rectilinearly running portions of the edges of the flat surfaces can beformed, the distance of which portions is reduced in the longitudinaldirection as they approach the location of the minimum distance value.

In order, firstly, to be able to adapt the profile of a flat surface tothe configuration of the chain roller lying thereagainst and in order,secondly, to be able to provide an edge of the flat surface, which edgeis as kink free or/and as jump free as possible and therefore promotesentry of a tooth into the inner link intermediate space, in alongitudinal region of the inner link, which longitudinal region issituated between the connecting openings, the edge of at least one flatsurface can run in the width direction in a manner curved continuouslyin the same direction. The profile of the edge of the flat surface canthen be particularly readily adapted to the contour, which taperstowards the tooth tip, in particular of a pinion tooth if the curvedprofile of the edge of the flat surface is assigned changing radii ofcurvature along the width direction. The radii of curvature preferablybecome smaller with increasing distance from the location of the minimumdistance value, ¬i.e. the curvature of the respective edge portionbecomes greater. Then, in addition, the abovementioned radial protrusionof the flat surface over the cylindrical circumferential surface of achain roller assigned to the flat surface for contact therewith can alsobe realized with a curved edge profile. This preferably holds true forboth flat surfaces of the inner link.

In principle, it should not be ruled out that the depression region isof convexly curved design in a width region containing the connectingstraight line, when looking at the inner link inner side, for example iscurved about an axis of curvature parallel to the connecting straightline. However, a greater inner link intermediate space available forreceiving a tooth can be obtained with a depression region which, in awidth region containing the connecting straight line, has a flat surfaceregion. In principle, said flat surface region can be inclined. Tofacilitate the introduction of a tooth into the inner link intermediatespace, the inclination, if it is present, is preferably such that thelink distance, to be measured in the thickness direction, of the flatsurface regions of two inner links lying mirror symmetrically oppositeeach other of one and the same inner link member becomes greater towardsa side edge away from the minimum distance value in the width direction.However, a flat surface region which is orthogonal with respect to thethickness direction is preferred for providing as large a receivingvolume as possible of the inner link intermediate space.

The flat surface region, following the presented asymmetry of the innerlink, is preferably arranged offset towards a side edge region relativeto the connecting straight line in the width direction. The flat surfaceregion is preferably arranged offset towards that side edge region whichis situated closer to the location of the minimum distance value, andtherefore an insertion slope having a greater dimension in the widthdirection can be provided on the side edge portion on the inlet side forthe pinion tooth than on the side edge portion on the inlet side for theroller tooth, for example in the form of a chamfering. This facilitatesthe introduction of a pinion tooth into the inner link intermediatespace.

For simple but reliable definition of the distance between two innerlinks forming an inner link member and also furthermore as a definedaxle formation which can rotatably receive a chain roller, according toan advantageous development the connecting openings are radiallysurrounded within the flat surfaces surrounding them in each case bysleeve portions. The sleeve portions protrude in the thickness directionof the inner links over the flat surfaces surrounding said sleeveportions.

In order to obtain a bicycle chain which is as slender as possible inthe thickness direction of the links forming the latter, the outer sideof the inner link that is opposite the inner side preferably has a flatouter surface which both extends in the longitudinal direction betweenthe connecting openings, where, during a shifting operation, a sidesurface of a pinion tooth of a pinion coming into engagement by means ofthe shifting operation can enter into contact engagement, and also atleast partially surrounds the connecting openings where inner sideregions of an outer link can come into contact with the completelymounted bicycle chain. The flat outer surface preferably completelysurrounds the connecting openings.

It is indeed in principle not ruled out that the outer side of the innerlink also has, in addition to the flat outer surface, a further,non-flat outer surface. However, in order to obtain the abovementionedslender bicycle chain, it is preferred that the outer side is free fromprojections which protrude over the flat outer surface in the thicknessdirection.

By contrast, it should not only not be ruled out, but it is evenpreferred that the outer side of the inner link has hollows ordepression surrounding the connecting openings and in whichcorresponding projections on inner sides of outer links can engage inorder to position the inner link and an outer link adjoining the latterrelative to each other. In order also to obtain a centering effect, thedepressions are preferably formed tapering in a direction away from theflat outer surface. For example, the depressions can have a negativelyfrustoconical configuration.

For the proposed inner link, it then advantageously does not matter forthe running direction of the bicycle chain formed with the participationof said inner link if the inner side or/and the outer side, preferablythe entire inner link, is mirror symmetrical with respect to a plane ofsymmetry orthogonal with respect to the connecting straight line.

The abovementioned object is also achieved by a bicycle chain outer linkhaving two connecting openings which are formed at a distance from eachother, pass through the outer link in the thickness direction thereofand are each designed for receiving a connecting component in order toconnect the outer link to a further outer link in order to form an outerlink member of a bicycle chain, wherein a connecting straight lineconnecting respective center axes of the connecting openings defines alongitudinal direction of the outer link, and wherein a directionorthogonal both with respect to the longitudinal direction and withrespect to the thickness direction is a width direction of the outerlink, wherein the outer link has, on its inner side facing the furtherouter link of the same outer link member in the completely mounted statein a bicycle chain, two flat surfaces which are provided at a distancefrom one another in the longitudinal direction of the outer link and areseparated by a depression region, which is placed in the longitudinaldirection between them, of which each flat surface surrounds another ofthe connecting openings, wherein the depression region is set back withrespect to the flat surfaces towards an outer side of the outer linkthat is opposite the inner side, wherein, in a minimum distance regioncontaining the connecting straight line and extending in the widthdirection, the distance, to be measured in the longitudinal direction,between the flat surfaces is minimal, wherein the distance between theflat surfaces starting from the minimum distance region becomes largertowards each of the two side edges bounding the outer link in the widthdirection.

Such an outer link can facilitate the introduction of a pinion toothinto the outer link intermediate space. The depression regions of outerlinks which are opposite one another in the thickness direction and areconnected by connecting components to form an outer link member of abicycle chain form a region on the outer link member, in which regionthe outer link member has a greater link distance, to be measured in thethickness direction, than, for example, in the region of the flatsurfaces which are designed for contact against outer sides of innerlinks. By means of the expansion of the depression regions in theapproach towards the side edges bounding the outer link in the widthdirection, the depression regions can act as introduction funnels forpinion teeth, and starting from virtually any arrangement of a piniontooth tip in the entry region of an outer link intermediate space, canguide pinion teeth into said intermediate space.

What has been stated at the beginning with regard to the connectingcomponents of inner link members holds true for the connectingcomponents of outer link members.

The distance between the flat surfaces does not have to become smallercontinuously from the side edge as far as the minimum distance region.It is entirely sufficient if a change in the distance between the flatsurfaces substantially takes place in a region situated close to therespective side edge. As a result, an advantageously stiff outer linkcan be obtained. Depending on how the edge of the respective flatsurfaces runs in the region in which the flat surfaces are adjacent tothe depression region in the longitudinal direction, an outer link whichboth promotes the entry of a pinion tooth into the outer linkintermediate space and is also advantageously stiff can be obtained inthat, for at least one width region of the outer link, it holds truethat a distance, to be measured in the longitudinal direction, betweenportions of edges, which are adjacent to the depression region, of theflat surfaces changes more greatly in the 50%, preferably 30%,particularly preferably 10% of the width dimension of the width regionthat is situated closest to the longitudinal center of the side edgethan in the 30%, preferably 40%, particularly preferably 50% of thewidth dimension of the width region that is situated closest to theconnecting straight line.

Said width region of the outer link extends from the connecting straightline parallel to the width direction as far as the longitudinal centerof a side edge. Consequently, the outer link has two width regions, oneon each side of the connecting straight line. What has been stated abovepreferably holds true for both width regions of an outer link.

For a bicycle chain, it is important that inner and outer link memberswhich are connected to one another in an articulated manner via aconnecting component can be safely bent about the axis of the connectingcomponent. The neat revolution of the chain around sprockets, pinionsand rollers of different diameters can thereby be ensured. This ensuresthat the bicycle chain remains in engagement with the respective toothcarrying components of the bicycle and is not inclined, for example, tojump from a sprocket or a pinion. One reason for an undesirablestiffening of a bicycle chain within the context of increased bendingresistance is a penetration of particles into the region between surfaceportions of inner and outer link lying against one another.

A configuration of the outer link which promotes both entry of a piniontooth into the outer link intermediate space and also counteracts entryof particles between said surface portions of inner and outer link canadvantageously be achieved by the fact that the distance between theflat surfaces on the inner side of the outer link increases more greatlyin the direction of the one side edge on a first side of a referenceplane orthogonally intersecting the connecting straight line in itslongitudinal center than on the opposite, second side of the referenceplane. As a result, the edge of a flat surface can run congruently withthe outer edge of an end portion of an inner link, said end portionlying against said flat surface, and the edge of the second flatsurface, which is situated away in the longitudinal direction, canprotrude with respect to a center axis, running in the thicknessdirection, of the connecting opening, which is surrounded by said flatsurface, radially over the outer edge of an end portion of another innerlink, said end portion lying against said other flat surface. Thisradial protrusion prevents particles which are entrained, for example,by way of a soiled pinion tooth tip from approaching the gap existingbetween outer link and inner link.

Said radial protrusion does not exist, or exists in a smaller extent, onthe first mentioned flat surface on the inner side of the outer link andthat end portion of the inner link which lies there against.Nevertheless, even in the case of congruent edges of the flat surface ofthe outer link inner side and end portion of the inner link outer side,which edges are preferably chamfering free in order to avoid dirtentering the gap between the inner and outer link, a narrow gap sizebetween the flat surface and end portion of the inner link can still bemaintained. This counteracts the entry of particles or even of a portionof a tooth tip into the gap. In the event of a congruent design, in saidregion both the edge of the flat surface of the outer link inner sideand the outer edge of the adjacent end portion of the inner link outerside are preferably formed in a circular manner with the center axis ofthe connecting component as center axis of the circular configuration.The congruence of the edge portions is then maintained over apredetermined relative movement portion of inner and outer linkirrespective of a relative rotation of outer link and inner link.

The distance preferably also increases to a differing extent in theopposite direction towards the respective other side edge on thedifferent sides of the reference plane, specifically particularlypreferably to a greater extent on the second side of the reference planethan on the first side thereof.

Tapering of the depression region from a side edge portion in the widthdirection towards the connecting straight line can be obtained under theabovementioned boundary conditions of an outer link which is not mirrorsymmetrical and has advantageously jump and kink free edges of a flatsurface in a region adjacent to the depression region in that, for theflat surface, it holds true that a region of the edge of the flatsurface that is adjacent to the depression region is curved to adiffering degree in the width direction on different sides of theconnecting straight line. This preferably holds true for the two flatsurfaces of the inner side of the outer link, which flat surfaces eachsurround a different connecting opening.

A radial protrusion of a flat surface on one side of the connectingstraight line and a smaller radial protrusion or a profile of the edgeof the flat surface, which profile is congruent with the outer edge ofthe adjacent inner link, on the other side of the connecting straightline can be obtained in that, for the flat surface, it holds true thatthat region of the edge of the flat surface that is adjacent to thedepression region has a curved profile in portions in the widthdirection on one side of the connecting straight line and a rectilinearprofile in portions on the other side. This preferably holds true forthe two flat surfaces. This will be explained using the example of achain joint which is formed by an outer link member and an inner linkmember which is connected to the latter and trails in the drivingdirection of rotation of the chain ring formed by the bicycle chain. Onaccount of the trailing in the driving direction of rotation, the chainroller of the chain joint and optionally outer edge regions of the innerlinks holding the chain roller between them in the width direction arepermanently in torque transmitting contact engagement with a piniontooth during a meshing engagement with a pinion. It can be advantageousthere to form the flat surfaces of the outer link inner sides, whichflat surfaces surround the connecting openings involved in the formationof said chain joint, on that side of the chain joint which faces thepinion axis, i.e. which are situated radially on the inside on the chainring, with a high radial protrusion with respect to the outer edges ofthose end regions of inner link outer sides which lie thereon. Bycontrast, on that side of the chain joint which is situated radially onthe outside of the chain ring, and also on that side of the chain joint,which leads in the driving direction of rotation, of the same outer linkmember that is situated radially on the inside, the mechanically lessgreatly loaded edges, which are therefore also less greatly exposed to arisk of soiling, of the flat surfaces can be formed with a smallerradial protrusion or congruently with the outer edge of the adjacentinner link end regions. Consequently, on the leading chain roller withrespect to the observed outer link intermediate space, an enlarged entryregion into the intermediate space is provided for a pinion tooth on theradially inner side of the chain ring.

The outer link can therefore be designed in accordance with the aboveexplanations in such a manner that a curved edge region portion of therespective other flat surface lies opposite that edge region portionwhich is rectilinear in portions in the longitudinal direction.Conversely, the same preferably holds true for the curved region of theedge of the same flat surface, i.e. that a rectilinear portion of anedge of the other flat surface lies opposite said curved region in thelongitudinal direction.

In principle, for easier introduction of a pinion tooth into the outerlink intermediate space, it is advantageous if, in a first width regionof the outer link, which width region extends from the connectingstraight line parallel to the width direction as far as the longitudinalcenter of the one side edge, the distance between edge portions of theflat surfaces that are adjacent to the depression region is at a maximumin the region of the longitudinal center of the one side edge. Foreasier production of an engagement even of a roller tooth with the outerlink intermediate space, with the roller tooth, by comparison with apinion tooth, entering the outer link intermediate space from theopposite direction in the width direction, it can therefore beadvantageous if in a second width region of the outer link, which widthregion extends from the connecting straight line parallel to the widthdirection in the opposite direction as far as the longitudinal center ofthe other side edge, the distance between edge portions of the flatsurfaces that are adjacent to the depression region is at maximum in theregion of the longitudinal of the other side edge. To facilitate themounting of such an outer link during the production of a bicycle chain,the maximum distances in the first and in the second width region arepreferably identical in size in terms of amount.

To facilitate an accurately fitting arrangement of outer link and innerlink during the production of a bicycle chain, each of the connectingopenings of the outer link on the inner side is preferably surroundedradially within the flat surface surrounding them by a projectionprotruding in the thickness direction over the respective flat surface.On the finished bicycle chain, said projection preferably projects intothe abovementioned depression on the outer side of an inner link andthus defines the relative position of outer link and inner link withrespect to their connecting openings, which are each aligned in order toform a chain joint. The projection is preferably designed tapering in adirection away from the respective flat surface, and therefore, inparticular in interaction with a depression tapering in the thicknessdirection into the inner link, said projection can deploy a centeringeffect. The projection is preferably frustoconical.

Whenever the outer link has a depression region which is not mirrorsymmetrical, to facilitate the mounting of said outer link, it isnevertheless preferably provided that the inner side or/and the outerside, preferably the entire outer link, is point symmetrical withrespect to an axis of symmetry intersecting the connecting straight linein the longitudinal center thereof and running in the thicknessdirection. Symmetry present on the outer link eliminates the possibilityof an erroneous arrangement of the outer link on the bicycle chain.

For the facilitated mounting of the outer link with a considerablyreduced risk of error, it is therefore particularly preferred that theinner side or/and the outer side, preferably the entire outer link, ismirror symmetrical both with respect to a first plane of symmetryorthogonally intersecting the connecting straight line in thelongitudinal center thereof and with respect to a second plane ofsymmetry running in the thickness direction and containing theconnecting straight line.

In addition, the present invention relates to a chain ring, comprising abicycle chain revolving in a self-contained manner and having outer andinner link members following one another in an alternating manner in therevolving direction, wherein the inner link members are formed from twoasymmetric inner links, as described above, or/and wherein the outerlink members are formed from two outer links designed as describedabove. Such a chain ring also embodies the technical advantagesassociated with the present invention and achieves the object mentionedat the beginning on account of the use of the links presented above.

As has already been described in detail above, the above describedasymmetric inner link serves especially for forming preferred inner linkmembers which, with their one side edge, permit an extremelyadvantageous meshing engagement with a pinion of a rear wheel pinioncassette and which, with their side edge respectively opposite in thewidth direction, permit a particularly advantageous engagement with achain guiding roller of a derailleur. Inner link members consisting ofinner links, the two side edge portions of which are at a distance ofdiffering size from the connecting straight line in the width direction,are arranged on the chain ring, in order to obtain the advantageousengagement situations mentioned both with pinions and with the chainguiding roller, in such a manner that the side edge portions at thegreater distance from the connecting straight line are arranged lyingradially on the outside of the chain ring. This is because, during arevolution of the chain ring on a bicycle, the radially outer side ofthe chain ring is situated closer to a body of the chain guiding roller,while, during said revolution, the radially inner side of the chain ringis situated closer to a body of the meshing pinion of the rear wheelpinion arrangement.

In an embodiment, a bicycle chain inner link has two connecting openingswhich are formed at a distance from each other, pass through the innerlink in the thickness direction thereof and are each designed forreceiving a connecting component in order to connect the inner link to afurther inner link in order to form an inner link member of a bicyclechain, wherein a connecting straight line which connects respectivecenter axes of the connecting openings defines a longitudinal directionof the inner link, and wherein a direction orthogonal both with respectto the longitudinal direction and also with respect to the thicknessdirection is a width direction of the inner link, wherein the inner linkhas, on its inner side facing the further inner link of the same innerlink member in the completely mounted state in a bicycle chain, two flatsurfaces which are provided at a distance from each other in thelongitudinal direction of the inner link and are separated by adepression region, which is placed in the longitudinal direction betweenthem, and of which each flat surface surrounds another of the connectingopenings, wherein the depression region is set back with respect to theflat surfaces towards an outer side of the inner link that is oppositethe inner side.

In FIG. 1, a bicycle is denoted in general by 10. The bicycle 10comprises a bicycle frame 12 with a front wheel 14, a rear wheel 16,handlebars 18 and a saddle 20. As customary in the case of bicycles,torque can be introduced on the bicycle 10 via pedals 22 and cranks 24into a front sprocket 26 which is transmitted via a bicycle chain 30,which revolves in a self-contained manner in the form of a chain ring28, to a multiple pinion arrangement 32 on the rear wheel 16. Duringforwards travel, the bicycle chain 30 revolves in the clockwisedirection in FIG. 1 along the driving direction of rotation D.

The pinion of the multiple pinion arrangement 32 on the rear wheel 16that meshes in each case with the bicycle chain 30 can be selected in amanner known per se by means of a derailleur 34 which is movable alongthe rear wheel axle A. This is not intended to mean that the derailleur34 is movable only along the rear wheel axle A. On the contrary, it isalso movable along the rear wheel axle A.

The derailleur 34 comprises a chain tensioning roller 36 which issituated further away from the pinion arrangement 32 and ensures thatthe chain ring 28 does not have any slack. The derailleur 34 furthermorecomprises a chain guiding roller 38 which is situated closer to thepinion arrangement 32 and positions the chain 30 or the chain ring 28along the rear wheel axle A with respect to the pinion arrangement 32.

The bicycle chain 30 is formed in a manner known per se by a pluralityof outer link members 40 which follow one another in the longitudinaldirection L of the chain and between which a respective inner linkmember 42 is arranged which connects the outer link members 40 to oneanother.

In FIG. 2, the front sprocket 26 and the chain ring 28 are illustratedmerely in roughly schematic form. But the derailleur 34 and the pinionarrangement 32 are illustrated in more detail than in FIG. 1.

In the example illustrated, the pinion arrangement 32 is an 11 timespinion arrangement 32 having 11 coaxial pinions 32 i, where i=1 to 11.In FIG. 2, the bicycle chain 30 meshes with the pinion 32 1 of largestdiameter. From each of the pinions 32 1, pinion teeth 33 protruderadially outwards with respect to the rear wheel axle A. Roller teeth 39are formed on the chain guiding roller 38, which roller teeth protrude,with respect to the axis of rotation of the chain guiding roller 38,radially from a roller body 37 of the chain guiding roller 38. In adeparture from the schematic illustration of FIG. 2, the pinion teeth 33can have a greater tooth height than the roller teeth 39.

The revolving chain ring 28 has a radially inner side 28 1 and has aradially outer side 28 2 further away from the area enclosed by thechain ring 28. As can be seen in FIG. 2, the front sprocket 26, thepinions 32 i and the tensioning roller 36 mesh with the revolving chainring 28 in such a manner that the teeth thereof each engage in theintermediate spaces of the link members 40 and 42 from the radiallyinner side 28 1 of the chain ring 28. By contrast, the teeth 39 of thechain guiding roller 38 enter the intermediate spaces of the linkmembers 40 and 42 from the radially outer side 28 2.

For further explanation, FIG. 3 illustrates a meshing engagement of thebicycle chain 30 with the front sprocket 26. The sprocket 26 is drivenin the direction of rotation DD by the cyclist via the pedals 22 and thecranks 24, as a result of which teeth 26 1 and 26 2 successively enterinto engagement with outer link members 40 and inner link members 42.The teeth 26 1 are each shaped identically, as are the teeth 26 2. Theteeth 26 1 are thinner here than the teeth 26 2 of the sprocket 26.Accordingly, the teeth 26 1 are provided for engagement in the narrowerinner link intermediate space and the teeth 26 2 for engagement in thewider outer link intermediate space.

The outer link members 40 and the inner link members 42 are eachconnected to one another via a connecting pin 44, wherein link members40 and 42 directly connected to one another by a connecting pin 44 canbe angled around the connecting pin 44 and therefore form a chain joint46 at the connecting pin 44. In the thickness direction T of the linkmembers 40 and 42 or of the bicycle chain 30, a chain joint 46 comprisesa central rotatable chain roller 48 which is enclosed in the thicknessdirection T on both sides by a respective inner link 50. In thethickness direction T in turn, the two inner links 50 of an inner linkmember 42 are each adjacent on their side facing away from the chainroller 48 to an outer link 52. The two outer links 52 of an outer linkmember 40 are preferably formed and arranged mirror symmetrically withrespect to a mirror plane orthogonal to the thickness direction T.Similarly, the inner links 50 of an inner link member 42 are preferablyformed and arranged mirror symmetrically with respect to said mirrorplane.

The bicycle chain 30 shown in FIG. 3 reproduces said links only inroughly schematic form. Details of the configuration of the links 50 and52 are explained in the following figures.

FIGS. 4A to 4D show a first embodiment of an inner link 50. FIG. 4Ashows a top view of an inner side, which faces an opposite, identicalinner link 50 in the inner link member 42, when looking at said innerside along the thickness direction T. FIG. 4B shows a view of the innerlink 50 along the width direction B, when looking at that side of theinner link 50 which forms the radially inner side 28 1 of the chain ring28, along the arrow IV B from FIG. 1. FIG. 4C shows a view of the innerlink 50 likewise along the width direction B, but from the oppositedirection as in FIG. 4B, i.e. when looking at that side of the innerlink 50 which forms the radially outer side 28 2 of the chain ring 28,along the arrow IV C from FIG. 1. FIG. 4D shows a perspective view ofthe outer side opposite the inner side from FIG. 4A in the thicknessdirection T.

FIG. 4A shows two connecting openings 54 and 56 which, in the completelymounted state of the bicycle chain 30 or of the chain ring 28, are eachpassed through by a connecting component in an exemplary configurationof a connecting pin 44. Center axes passing centrally through theconnecting openings 54 and 56 and running parallel to the thicknessdirection T are denoted by M54 and M56, respectively. A connectingstraight line V which connects the two center axes M54 and M56 and isorthogonal with respect to the two center axes M54 and M56 forms areference straight line in the description of the inner link 50. Theconnecting straight line V defines a longitudinal direction L of theinner link 50, said longitudinal direction on the completely mountedbicycle chain 30 always coinciding with the local longitudinal directionL of the bicycle chain 30.

The connecting straight line V extends from the center axis M54 as faras the center axis M56. Since the inner link 50 is of mirror symmetricaldesign with respect to a plane SE orthogonally intersecting theconnecting straight line V in its longitudinal center LM, thedescription of half of the inner link 50 suffices. The respective otherhalf is apparent from said condition of mirror symmetry.

Each of the connecting openings 54 and 56 is surrounded by a sleeve likecollar 58 or 60 which, on the finished inner link member 42, forms partof an axle which rotatably supports the chain roller 48 assigned to therespective connecting opening. Each sleeve like collar 58 or 60 issurrounded by a flat surface 62 or 64, against which the chain roller 48assigned to the respective connecting opening 54 or 56 lies with itspreferably likewise flat end side or at least lies opposite saidsurface.

The flat surface 62 is bounded radially outward by an edge 66, and theflat plane 64 by an edge 68. The edges 66 and 68 can be located closerto the respective surrounding connecting openings 54 and 56,respectively, than an edge 70 of the inner link 50 since chamferings 72can be situated between the edge 70 of the inner link 50 and the edges66 and 68 of the flat surfaces 62 and 64.

Between the connecting openings 54 and 56, a side edge portion 70 1 ofthe inner link edge 70 extends on the side assigned to the radiallyinner edge 28 1 of the chain ring 28, and a side edge portion 70 2 ofthe inner link edge 70 extends on the side assigned to the radiallyouter edge 28 2 of the chain ring 28.

The side edge portions 70 1 and 70 2 are at differing distances from theconnecting straight line V in the width direction B. In case of doubt,the distance of a side edge portion should be determined as the distancefrom the longitudinal center LM of the connecting straight line V. Fromthe latter, the side edge portion 70 1 which is concave when viewing theradially inner side 28 1 of the chain ring 28 is at the shorter distance“ab” away from the longitudinal center LM of the connecting straightline V. By contrast, the opposite side edge portion 70 2 is at thegreater distance “AB” away from the longitudinal center LM of theconnecting straight line V.

A depression region 74 is formed in the region between the flat surfaces62 and 64, said depression region being set back with respect to theflat surfaces 62 and 64 towards the outer side of the inner link 50. Bycontrast, the flat surfaces 62 and 64 lie in a common plane. Thedepression region 74 together with the depression region 74 of theopposite inner link 50 of an inner link member 42 forms a substantialpart of an inner link intermediate space.

Past the side edge portion 70 1, a pinion tooth 33 enters the inner linkintermediate space in the region of the depression portion 74. Past theside edge portion 70 2, a roller tooth 39 of the chain guiding roller 38enters the inner link intermediate space in the region of the depressionportion 74. Independently of on which pinion 32 i the pinion tooth 33 isformed, the latter generally has a greater tooth height than a rollertooth 39.

In order, even in the case of a shorter tooth height of a roller tooth39, to be able to readily guide an inner link member 42 on the guideroller 38 although the bicycle chain 30 only has a very small dimensionin the thickness direction T of the chain links, the side edge portion70 2 is of rectilinear design and is further away from the connectingstraight line V than the opposite side edge portion 70 1. Therefore,even in the event of a short tooth height of a roller tooth 39, a largeoverlap between the roller tooth 39 and the inner link 50 in the widthdirection B can be achieved. In addition, the rectilinear side edgeportion 70 2, which is preferably parallel to the connecting straightline V, can lie as a tangent against a conical lateral surface of aroller body 37, frequently in the form of a double truncated cone, ofthe chain guiding roller 38. The roller body 37 generally tapers herefrom the plane of the roller teeth 39 axially towards the two oppositesides. Each side edge portion 70 2 of two inner links 50 forming aninner link member 42 can therefore lie against another truncated cone ofthe roller body 37.

The reference number 76 denotes the location of the smallest distance inthe longitudinal direction L between the edges 66 and 68 of the flatsurfaces 62 and 64. Said location 76 of the minimum distance valuebetween the edges 66 and 68 of the two flat surfaces 62 and 64 andtherefore between the flat surfaces 62 and 64 is situated closer in thewidth direction B to the side edge portion 70 2 than the connectingstraight line V. As a result, from the side edge portion 70 1, a piniontooth 33 with a comparatively high tooth height can penetrate the innerlink intermediate space, which is essentially provided by the depressionregion 74, and, via its complete tooth height, is not only optimallyguided into the inner link intermediate space, but also is heldvirtually in a form fitting manner in the inner link intermediate space.The chain 30 is therefore very readily guided by an inner link member 42on a pinion 32 i and can optimally transmit force, and therefore torque,to the pinion arrangement 32 and therefore to the rear wheel 16.

In the width direction B, the distance in the longitudinal directionbetween the flat surfaces 62 and 64 increases again on both sides of thelocation 76 of the minimum distance value between the flat surfaces 62and 64. In the example illustrated, a location of greatest distance ofthe flat surfaces 62 and 64 from each other in the longitudinaldirection L is in each case present on each side of the connectingstraight line V where a distance straight line running in thelongitudinal direction lies tangentially against the two edges 66 and68. This is the location 78 of a maximum distance value on the side ofthe side edge portion 70 1 and the location 80 of maximum distance valueon the side of the side edge portion 70 2. Said maximum distance valuesat the locations 78 and 80 are preferably identical in size in terms ofamount. Similarly, the locations 78 and 80 of the maximum distancevalues in the width direction B can be equally far away from theconnecting straight line V. Consequently, the location 76 of the minimumdistance value is also at different distances away from the locations 78and 80 of the maximum distance values. This also supports theimprovement of the guiding of the chain by inner link members 42 onpinions 32 i, on the one hand, and on the chain guiding roller 38, onthe other hand. The cost of said improved guidance of the inner linkmembers 42 on the pinions 32 i and on the chain guiding roller 38 is theasymmetry of the inner links 50 in the width direction B.

The edge 66 and the edge 68 of the flat surfaces 62 and 64,respectively, each have a respective rectilinear portion 66 1 and 68 1which lie opposite each other in the longitudinal direction L because ofthe abovementioned mirror symmetry of the inner link 50. The rectilinearedge region 66 1 and 68 1 diverge from the location 76 of the minimumdistance value towards the side edge portion 70 1. As a result, thedepression region 44 in its extent in the longitudinal direction and inthe width direction is approximate to the shape of a pinion tooth 33which customarily tapers towards the tooth tip.

Therefore, in the region of the minimum distance value 76, zones 82 and84 of a radial protrusion of the flat surface 62 and of the flat surface64, respectively, over the cylindrical outer casing of the chain guidingroller 38, which is in each case adjacent to the flat surfaces 62 and64, can be obtained.

From the location 79, which is situated closest to the side edge portion70 1, of greatest distance of the edge 66 away from the edge 68 of theflat surface 64, which is situated in the longitudinal direction L onthe opposite side of the depression region 74, as far as the location81, which is situated closest to the side edge portion 70 2, of greatestdistance away from the edge 68, edge regions of greater curvature (witha smaller radius of curvature) alternate with edge regions of smallercurvature (with a greater radius of curvature). Rectilinear regions areconsidered here as edge regions of curvature 0, i.e. with an infinitelylarge radius of curvature. The edge 66 is curved to the greatest extentin the region 82 of the radial protrusion, which permits the radialprotrusion with a step and kink free boundary. At the points 79 and 81,the curvature of the edge 66 is in each case greater than in the edgeregions directly adjacent to the depression region 74. Starting from thepoint 79 towards the rectilinear region 66 1, first of all a weak,curved region 66 3 follows, followed in turn by a region 66 2 which iscurved to a greater extent and finally leads into the rectilinear region66 1. The same holds true for the edge 68 because of the mirror symmetrymentioned.

As FIG. 4D shows, the outer side of the inner link 50 has a flat surface86 which firstly extends in the longitudinal portion between theconnecting openings 54 and 56 and which surrounds each of the connectingopenings 54 and 56. The flat surface 86 on the outer side of the innerlink 50 is preferably a flat surface 86 joined continuously together.Negatively frustoconical hollows or depressions 88 and 90 are formed onthe outer side of the inner link 50 in a manner directly surrounding therespective connecting openings 54 and 56.

The material displaced in the region of the depressions 88 and 90 duringthe deformation of a metal plate to form the inner link 50 hasadvantageously been used here to form the sleeve like collars 56 and 60.On the finished bicycle chain 30, the depressions 88 and 90 receivecorresponding projections on inner sides of outer links 52, whichprojections, advantageously designed in a positively frustoconicalmanner, center the connecting openings, which are likewise present onouter links 52 for receiving the connecting pins 54, with respect to theaxes M54 and M56. The axes M54 and M56 are simultaneously axes ofarticulation of the chain joints 46 formed by the respective connectingpins 44, and therefore the centering of inner links 50 and outer links52 with respect to said axes M54 and M56 is particularly advantageous.

In a width region 74 3 containing the connecting straight line V, thedepression region 74 can be configured to be flat and preferablyparallel to the flat surface 86 of the outer side. By contrast, inadjoining width regions 74 1 and 74 2 towards the side edge portion 70 1and 70 2, respectively, the depression region 74 can be formed as aninsertion aid for a pinion tooth 33 (width region 74 1) or for a rollertooth 39 (width region 74 2) falling in a chamferingled or sphericallyconvexly curved manner towards the respective side edge portion. Onaccount of the possible different tooth heights, the width region 74 1of the depression region 74, which width region is assigned to thepinion tooth 33, as insertion aid in the width direction B preferablyhas a greater dimension than the width region 74 2 assigned to a rollertooth 39 as insertion aid.

FIG. 5 illustrates a second embodiment of an inner link when looking atthe inner side along the thickness direction T as viewing direction.Identical and functionally identical components and component portionsas on the inner link of the first embodiment are provided with the samereference numbers in FIG. 5, but increased by 100.

The second embodiment of an inner link 150 from FIG. 5 will be explainedbelow only to the extent that it differs from the configuration of thefirst embodiment, to the description of which otherwise reference isalso made for explaining the second embodiment.

The embodiment of the inner link 150 from FIG. 5 corresponds to theinner link 50 of FIGS. 4A to 4D except for one detail: the location 176at which the distance in the longitudinal direction L between the flatsurfaces 162 and 164 is minimal is not only a point shaped coordinate inthe width direction B without a significant width dimension, but is aregion 176 in which the minimum distance value does not change. Saidregion 176 extends in the width direction B in such a manner that itcontains the connecting straight line V, wherein the distance of theparallel region edges, which run in the longitudinal direction L, fromthe connecting straight line V differs in size. The region edge situatedcloser to the side edge portion 170 1 therefore is at a considerablyshorter distance from the connecting straight line V than the regionedge situated closer to the opposite side edge portion 170 2. Thedistances can be 1 to 2 or more, preferably 1 to 3 or more. Also in theembodiment of FIG. 5, the location of a minimum distance value betweenthe two flat surfaces 162 and 164 or between their respective edges 166and 168 therefore extends as far as a location which is situated at adistance away from the connecting straight line V. In the widthdirection B on both sides of the minimum distance value region 176, theflat surfaces 162 and 164 are at greater longitudinal distances fromeach other than in the region 176. The locations 178 and 180 of maximumdistance values on each side of the connecting straight line V again lieat the point where the respective distance straight line liestangentially against the edges 166 and 168.

In the second embodiment of the inner link 150, the rectilinear edgeportions 166 1 and 168 1 run parallel to each other in the widthdirection B beyond the region 176. The end situated closer to the sideedge portion 170 2 in the width direction B of the minimum distancevalue region 176 lies further away from the side edge 170 2 than is thecase for the location 76 of the first embodiment of the inner link 50from FIG. 4A. The regions of radial protrusion 182 and 184 over thecylindrical outer surface of the chain rollers 148 lying opposite therespective flat surfaces 162 and 164 are therefore less greatly distinctthan in the embodiment of FIG. 4A.

As can already be seen in the embodiment of the inner link 50 from FIG.4A, curved edge regions which have different radii of curvature alongtheir profile adjoin the rectilinear edge regions 166 1 and 168 1 onboth sides in the width direction B.

FIG. 6 illustrates a third embodiment of an inner link. A top view ofthe inner side of the inner link 250 when viewing same in the thicknessdirection T can be seen in FIG. 6—as in FIG. 4A and in FIG. 5.

Identical and functionally identical components and component portionsas in FIGS. 4A and 5 are provided in FIG. 6 with the same referencesigns, but increased by 200 or 100. The third embodiment of FIG. 6 willbe explained below only to the extent that it differs from the precedingillustrations of identical perspective of FIGS. 4A and 5, to thedescription of which reference should expressly otherwise also be madefor the explanation of FIG. 6.

First of all, it is noticeable that the flat surfaces 262 and 264 arecompletely surrounded by a chamfering 272 and by the depression region274 and therefore no regions of the flat surfaces 262 and 264 extend asfar as the edge 270 of the inner link 250. However, the flat surfaces262 and 264 can be designed in this regard to differ from theillustration of FIG. 6, like the flat surfaces 62 and 64 or 162 and 164of the preceding embodiments.

In a departure from the second embodiment of the inner link 150 and inaccordance with the first embodiment of an inner link 50, the location276 of greatest convergence of the flat surfaces 262 and 264 with eachother in the longitudinal direction L is a specific coordinate in thewidth direction B and is not an extended region with a significantdimension in the width direction B. Since the distance of the flatsurfaces 262 and 264, like the flat surfaces 62 and 64 or 162 and 164,is synonymous with the distance of the edges 266 and 268 from each otherin the longitudinal direction L, the location 276 of the minimumdistance value between the flat surfaces 262 and 264 is also a locationof the minimum distance value between the edges 266 and 268 bounding therespective flat surfaces 262 and 264 radially on the outside withrespect to the respective center axes M254 and M256.

Unlike in the preceding embodiments, no rectilinear edge portions of theedges 266 and 268 adjoin the location 276 of the minimum distance value.Wherever the edges 266 and 268 are directly adjacent to the depressionregion 274, said edges run with a curved profile having different radiiof curvature. Specifically at the location 276 of the minimum distancevalue, the radius of curvature of the respective edges 266 and 168 canbe at maximum with respect to edge regions following parallel to thewidth direction B on both sides of the location 276. Only in a regionsituated close to the side edge portion 270 2, away from the location276 of the minimum distance value, does a portion 266 1 or 268 1 of theedges 266 or 168 run rectilinearly. A profile which is rectilinear insections can also be formed on that portion of the edges 266 and 268which is situated furthest away from the depression region 174 in thelongitudinal direction L.

The central portion 274 3 of the depression region 274 can in turn beformed flat or can be curved spherically, i.e. convexly in the top viewof FIG. 6, about an axis of curvature parallel to the connectingstraight line V. In the third embodiment, the chamfered regions 274 1and 274 2 have a greater width dimension along the width direction Bthan in the preceding first two embodiments. The regions 274 1 or/and274 2 can in turn be of flat design, but then preferably inclined in adirection away from the connecting straight line V towards the outerside of the inner link at 150, or likewise can be of spherical design,curved about an axis of curvature parallel to the connecting straightline V, wherein the radius of curvature of the regions 274 1 or/and 1742 is then smaller than that of the flat central portion 274 3 of thedepression region 274.

FIG. 7 illustrates an inner side of a first embodiment of an outer link52. Like the inner sides of the inner links 50, 150 and 250 of FIGS. 4A,5 and 6, the inner side of the outer link 52 of FIG. 7 is also viewedalong the thickness direction T.

Identical and functionally identical component portions of the outerlink 52 in comparison with the inner sides of inner links of FIGS. 4A, 5and 6 are denoted by the same reference numbers as in FIG. 4A, but areadditionally provided with the lower case letter “a”. Explanations ofsaid component portions in conjunction with the inner links 50, 150 and250 can also be applied because of their functional similarity or/anddesign similarity to component portions of identical reference sign onthe outer link 52.

The outer link 52 also has connecting openings 54 a and 56 a which areeach surrounded by a flat surface 62 a and 64 a, respectively. Centeraxes M54 a and M56 a which pass centrally in the thickness direction Tthrough the connecting openings 54 a and 56 a, respectively, arecollinear on the completely mounted bicycle chain 30 with thecorresponding center axes of the connecting openings 56 and 54,respectively, of inner links 50. The center axis M54 a of the outer link52 is collinear here with a center axis M56 of an inner link 50. Thecenter axis M56 a is correspondingly collinear with a center axis M54.

Each connecting opening 54 a and 56 a is surrounded by a frustoconicalprojection 55 a and 57 a, respectively, which, on the finished bicyclechain 30, project into the negatively conical depressions 88 and 90,respectively, and coaxially center the outer link 52 and the inner links50 there with respect to their respective center axes.

A portion of the flat surface 86 of the outer side of an inner link 50therefore in each case lies opposite the flat surfaces 62 a and 64 a. Inmore precise terms, a portion of the flat surface 86 of another innerlink 50 lies opposite each flat surface 62 a and 64 a.

Between the flat surfaces 62 a and 64 a, a depression region 74 a isalso formed on the inner side of the outer link 52, said depressionregion being offset in relation to the preferably coplanar flat surfaces62 a and 64 a away from the inner side toward the opposite outer side ofthe outer link 52.

Unlike in the case of the inner links 50, the flat surfaces 62 a and 64a of the outer links 52 are not surrounded by a chamfering, but ratherextend as far as the edge 70 a of the outer link 52. The side edgeportions 70 a 1 and 70 a 2 lying between the connecting openings 54 aand 56 a are at an identical distance away from the longitudinal centerLMa of the connecting straight line Va in the width direction B.

A region 76 a of minimum convergence of the two flat surfaces 62 a and64 a or of the edges 66 a and 68 a thereof in the longitudinal directionL is formed on the outer link 52 with a finite extent in the widthdirection B symmetrically about the connecting straight line Va. In bothdirections along the width direction B, the distance of the flatsurfaces 62 a and 64 a in the longitudinal direction L from each otherincreases with increasing distance away from the connecting straightline Va.

The outer link 52 has, on its inner side, two width regions, namely oneon each side of the connecting straight line Va. A first width regionBB1 begins at the connecting straight line Va and extends in the widthdirection B as far as the side edge portion 70 a 1 which, on thecompletely mounted chain 30, is situated on the radially inner side 28 1of the chain ring 28. A second width region BB2 likewise begins at theconnecting straight line Va and extends along the width direction B asfar as the opposite side edge portion 70 a 2, which is situated on theradially outer side 28 2 of the chain ring 28. Each width region BB1 andBB2 ends more precisely at that point X1 and X2 at which, in a top viewof the inner side of the outer link 52 according to FIG. 2, the sideedge portions 70 a 1 and 70 a 2 intersect a plane P orthogonallyintersecting the connecting straight line Va in its longitudinal centerLMa. The ends of each width region BB1 and BB2 are indicated by dottedlines in FIG. 7.

For the first width region BB1, it holds true that the distance of theedge 68 a of the flat surface 64 a from the plane P increases moregreatly with increasing distance away from the connecting straight lineVa in the width direction B than the opposite edge 66 a in thelongitudinal direction L.

It also holds true for the second width region BB2 that the distance ofthe edge 66 a of the flat surface 62 a from the plane P increases moregreatly with increasing distance away from the connecting straight lineVa in the width direction B than the distance of the edge 68 a. Theinner side of the outer link 52 is preferably spot symmetrical withrespect to an axis of symmetry which orthogonally intersects theconnecting straight line Va in its longitudinal center LMa and runs inthe thickness direction T.

Each edge 66 a and 68 a has a rectilinear portion 66 a 1 and 68 a 1 inthe width region BB1 or BB2, in which the distance of said edge from theplane B increases less greatly than the respective other edge. Therectilinear edge portions are preferably parallel to the plane P. In theother width region BB1 or BB2 in each case, the edges 66 a and 68 a eachhave a partially circular edge portion 66 a 2 and 68 a 2, respectively.

On the completely mounted bicycle chain, the partially circular edgeportions 66 a 2 and 68 a 2 are congruent with partially circularportions of the edge 70 of the inner link 50. On account of thepartially circular design of the two edges, said edges also remaincongruent if inner link members 42 and outer link members 40 are angledrelative to one another about their chain joints 46. In the region ofthe rectilinear edge portions 66 a 1 and 68 a 1, protrusions 82 a and 84a protruding radially with respect to the respective center axes M54 aand M56 a over the edges 70 of assigned inner links 50 are formed, saidprotrusions opposing a penetration of dirt into a gap space between theinner side of the outer link 52 and outer side of the inner link 50.

Since the bicycle chain 50 “pushes” pinion teeth 33 in order to transmittorque to the rear wheel 16, the radial protrusion 82 a is situatedcloser to the side edge portion 70 a 1 situated on the radially innerside 28 1 of the chain ring 28 than the opposite side edge portion 70 a2. In the event of a meshing engagement of an outer link member 40formed by the outer links 52, the radial protrusion 82 a is thereforelocated in the region of the tooth root of a pinion tooth 33 whichengages in an outer link intermediate space essentially formed by thedepression region 74 a.

The central region 74 a 3, containing the connecting straight line Va,of the depression region 74 a can in turn be of flat design,specifically preferably parallel to the flat outer side of the outerlink 52. Regions 74 a 1 and 74 a 2 which extend from the central region74 a 3 of the depression region 74 a as far as the respective side edgeportion 70 a 1 and 70 a 2 can in turn be designed as insertion slopesfor a pinion tooth 33 into the outer link intermediate space.

As FIG. 7 shows, the distance of the two edges 66 a and 68 a in thelongitudinal direction L from each other changes more greatly in the twowidth regions BB1 and BB2 in the outermost 30% width dimension in thewidth direction, which contains the respective end points X1 and X2,than in the innermost 30% width dimension, starting directly from theconnecting straight line Va, of each width region BB1 and BB2. Thechange of the distance of the edges 66 a and 68 a from each other in thelongitudinal direction L in a portion in the width direction B isdefined as the difference in the distances at the beginning and at theend of the portion, divided by the distance at the beginning of therespective portion.

FIG. 8 illustrates a second embodiment of an outer link, wherein FIG. 8shows the inner side of the outer link when looking along the thicknessdirection T. Identical and functionally identical components andcomponent portions as in FIG. 7 are provided with the same referencenumbers in FIG. 8, but increased by 100. The second embodiment of anouter link 152 of FIG. 8 will be described below only in so far as itdiffers from the first embodiment of the outer link 52 from FIG. 7, tothe description of which reference is otherwise also made for explainingthe second embodiment of FIG. 8.

In contrast to the point symmetrical inner side of the outer link 52,the inner side of the second embodiment of the outer link 152 is mirrorsymmetrical both with respect to the plane P and also with respect to aplane running in the thickness direction T and containing the connectingstraight line Va. The outer link 152 of the second embodiment cantherefore be mounted with a lower risk of error than that of FIG. 7since every mirror symmetry reduces the possibilities of an erroneousarrangement of a link on the bicycle chain 30. In addition, the outerlink 152 can lie opposite itself whereas the outer link 52 requires acounterpart which is mirror symmetrical with respect to a plane parallelto the plane of the drawing of FIG. 7 in order to form an outer linkintermediate space delimited in a mirror inverted manner in thethickness direction T.

In the second embodiment, the central region 176 a, in which the edges166 a and 168 a are at the smallest distance from each other in thelongitudinal direction L, has a greater dimension in the width region Bthan in the first embodiment. Rectilinear edge regions 166 a 1 and 168 a1 lie directly opposite each other in the longitudinal direction L. Thedistance of the edges 166 a and 168 a from each other increases alongthe width direction B on both sides of the region 176 a of minimumlongitudinal distance, wherein the change or increase in the secondembodiment is greater in the outermost 10% width dimension of the widthregion BB1 that contains the point X1 than in the innermost 50% widthdimension of the width region BB1 that contains the connecting straightline Va. For the width region BB2, the same correspondingly holds truebecause of said mirror symmetry with respect to the plane of symmetrycontaining the connecting straight line Va and running in the thicknessdirection T.

In a departure from the illustration of FIG. 8, the edges 166 a and 168a cannot have any rectilinear portion whatsoever at the location atwhich they are adjacent to the depression region 174 a, but rather caneach have a convex configuration, as viewed from the longitudinal centerLMa of the connecting straight line Va. The location 176 a of minimumdistance of the edges 166 a and 168 a from each other in thelongitudinal direction L then coincides with the connecting straightline Va.

Both in the configuration illustrated in FIG. 8 and in the alternativedescribed in the preceding paragraph, the radius of curvature of thecurvature of the edges 166 a and 168 a changes in the curved edgeportion of the edges 166 a and 168 a with increasing distance from thelocation 176 a of the minimum distance value towards radius valuesbecoming ever smaller, preferably until the edge 170 a of the outer link152 is reached.

In an embodiment, a chain ring (28) involves a bicycle chain (30)revolving in a self-contained manner and having outer and inner linkmembers (40, 42) following one another in an alternating manner in therevolving direction (D), wherein the inner link members (42) are formedfrom two asymmetric inner links (50; 150; 250), as is described herein,and/or the outer link members (40) are formed from two outer links (52;152) as is described herein. The inner link members (42) may be formedfrom two asymmetric inner links (50; 150; 250), wherein the side edgeportions (70 a 2; 170 a 2; 270 a 2) at the greater distance from theconnecting straight line (Va) are arranged lying radially on the outsideof the chain ring (28).

We claim:
 1. A bicycle chain inner link, comprising: two connectingopenings which are formed at a distance from each other, pass throughthe inner link in the thickness direction thereof and are each designedfor receiving a connecting component in order to connect the inner linkto a further inner link in order to form an inner link member of abicycle chain, wherein a connecting straight line connecting respectivecenter axes of the connecting openings defines a longitudinal directionof the inner link, and wherein a direction orthogonal both with respectto the longitudinal direction and also with respect to the thicknessdirection is a width direction of the inner link, wherein the inner linkhas, on its inner side facing the further inner link of the same innerlink member in the completely mounted state in a bicycle chain, two flatsurfaces which are provided at a distance from each other in thelongitudinal direction of the inner link; and are separated by adepression region, which is placed in the longitudinal direction betweenthem, and of which each flat surface surrounds another of the connectingopenings, wherein the depression region is set back with respect to theflat surfaces towards an outer side of the inner link that is oppositethe inner side, wherein a distance, to be measured along thelongitudinal direction, between the flat surfaces changes along thewidth direction in such a manner that a location situated between twodistance regions having in each case greater distance values and havingthe smallest, but finitely large minimum distance value is situated at adistance away from the connecting straight line in the width direction.2. The bicycle chain inner link according to claim 1, wherein in theregion of the longitudinal center of the connecting straight line, thedistances of those side edge portions of the inner link that run in thelongitudinal direction between the connecting openings away from theconnecting straight line in the width direction differ in size ondifferent sides of the connecting straight line.
 3. The bicycle chaininner link according to claim 2, wherein the side edge portion with thegreater distance away from the connecting straight line runsrectilinearly parallel thereto, and in that the opposite side edgeportion with the smaller distance away from the connecting straight linefirst of all along its profile in the longitudinal direction approachesthe connecting straight line and then moves away from the latter again.4. The bicycle chain inner link according to claim 3, wherein thelocation of the minimum distance value is situated closer in the widthdirection to a side edge portion of the inner link, which side edgeportion runs in the longitudinal direction between the connectingopenings link, than to the connecting straight line.
 5. The bicyclechain inner link according to claim 4, wherein the location of theminimum distance value is situated on the same side of the connectingstraight line on which the distance of the side edge portion away fromthe connecting straight line is greater.
 6. The bicycle chain inner linkaccording to claim 5, wherein, in the width direction on both sides ofthe connecting straight line, in each case at a distance from thelocation of the minimum distance value, there is in each case a locationof a maximum distance value at which the distance, which occurs on therespective side of the connecting straight line and is to be measured inthe longitudinal direction, between the two flat surfaces is greatest,wherein each of the two maximum distance values is greater in terms ofamount than the minimum distance value, and wherein the distance of thelocation of the minimum distance value away from the respectivelocations of the maximum distance values differs in size.
 7. The bicyclechain inner link according to claim 6, wherein, in a longitudinal regionof the inner link, which longitudinal region is situated between theconnecting openings, the edge of at least one flat surface runs or runrectilinearly at least in portions in the width direction.
 8. Thebicycle chain inner link according to claim 7, wherein, in thelongitudinal region, the edges of the two flat surfaces runrectilinearly at least in portions, wherein the rectilinear surface edgeregions run parallel to one another at least in portions.
 9. The bicyclechain inner link according to claim 7, wherein, in the longitudinalregion, the edges of the two flat surfaces run rectilinearly at least inportions, wherein the distance, to be measured in the longitudinaldirection, of the rectilinear surface edge regions is reduced at leastin portions in the width direction as they approach closer to thelocation of the minimum distance value.
 10. The bicycle chain inner linkaccording to claim 7, wherein, in a longitudinal region of the innerlink, which longitudinal region is situated between the connectingopenings, the edge of at least one flat surface runs or run in the widthdirection in a manner curved continuously in the same direction withradii of curvature changing along the width direction.
 11. The bicyclechain inner link according to claim 1, wherein the depression region, ina width region containing the connecting straight line, has a flatsurface region which is orthogonal with respect to the thicknessdirection.
 12. The bicycle chain inner link according to claim 11,wherein the flat surface region is arranged offset towards a side edgeregion relative to the connecting straight line in the width direction.13. The bicycle chain inner link according to claim 1, wherein theconnecting openings are surrounded radially within the flat surfacessurrounding them in each case by sleeve portions which protrude in thethickness direction of the inner links over the flat surfacessurrounding said sleeve portions.
 14. The bicycle chain inner linkaccording to claim 1, wherein the outer side of the inner link that isopposite the inner side has a flat outer surface which both extendsbetween the connecting openings and also surrounds the connectingopenings.
 15. The bicycle chain inner link according to claim 14,characterized in that the outer side is free from projections whichprotrude over the flat outer surface in the thickness direction.
 16. Thebicycle chain inner link according to claim 14, wherein the outer sidehas depressions surrounding the connecting openings, the depressionstapering in a direction away from the flat outer surface.
 17. Thebicycle chain inner link according to claim 1, wherein the inner sideand/or the outer side, is mirror symmetrical with respect to a plane ofsymmetry orthogonal with respect to the connecting straight line.